Study On The Hi-frequency Induction Brazing Of Diamond Tools

The brazing of PCD compact is the key procedure during the process of polycrystalline diamond cutting tools. Nowadays, the hi-frequency induction brazing is one of the most popular techniques used in the brazing of PCD compact around the world, due to its notable advantages, such as less pollution to the environment and higher production efficiency. Currently, previous studies focus mainly on brazing alloy and soldering flux, but little information is available about the effect of holding time on brazing procedure and its performance. Therefore, in order to enhance the performance of PCD cutting tools, it is essential to investigate the holding time and its impact on the hi-frequency induction brazing technique of PCD compact in details. Besides, the diamond cutting insert is increasingly becoming an indispensable tool because of its highest hardenss and wear resistance, however, the interfacial energy of diamond is so high that the brazing processability is very poor, so it is necessary to do some experimental research on the the brazing technique of diamond tool.The brazing of PCD compact in air was carried out respectively, using hi-frequency induction brazing machine. The effect of brazing temperature and holding time on the brazing of PCD quality were studied systematically in this paper, by means of self-made shearing equipment, as well as scanning electron microscopy (SEM) and electronic probe microscopy analysis (EPMA). Then, the thermal damage happening on the PCD cutting tools after brazing was analysed. On the other side, the comparative experiments of Ti-coated integral PCD were carried out in the atmosphere of air and inert gas.At first, the effect of holding time on the brazing processability of PCD compact was investigated, when the brazing temperature was 690℃. It is indicated that, when the holding time reaches 16s, the shearing strength reaches to the maximum, which is 340MPa, but the joint width diminish to 25μm. Secondly, in the same way, the effect of holding time on the PCD compact's brazing performance in the temperature of 720℃was analysed. It is found that the shearing strength is 336MPa in the holding time of 16s, which is a little lower than that of in the temperature of 690℃. Subsequently, the thermal damage happening on the PCD cutting tools after brazing was studied in different holding time and brazing temperature. It is concluded that, when the temperature is 690℃and holding time is 16s, there is a little damage on the surface of PCD compact. When the temperature is 720℃and holding time is 16s, the thermal damage is a little serious. When the holding time is 30s, both the 690℃and 720℃specimens are badly hurt, thus, the tool life is shortened. Last but not the least, the brazing experiments were carried out between the Ti-coated integral PCD and YG8 cemented carbide. It is indicated that the uncoated specimen in air has too much brazing defects. The Ti-coated specimen in air has a few defects. The Ti-coated integral PCD in the atmosphere of argon is successfully connected to the base material, because the argon effectively prevents the exposure of elements in air from oxidation.